The 12th Annual San Antonio Breast Cancer Symposium is an international meeting featuring state of the art lectures by invited speakers and proffered papers on the experimental biology, etiology, prevention, diagnosis and therapy of breast cancer. The symposium features concurrent clinical and basic science sessions as well as clinically oriented panel discussions during lunch. Abstracts accepted for presentation and manuscripts of plenary lectures are published in the journal BREAST CANCER RESEARCH AND TREATMENT. All symposia have been granted Category 1, AMA credit for continuing education. The 1988 symposium enrolled 418 registrants representing the United States and Canada, and fifteen foreign countries.